Bipolar disorder is a mental illness that manifests itself in cycles of mental ups and downs in a person.
It is also often called commonly called manic depression although
this name is not liked by psychiatrists because it implies that the cycles
are evenly split between mania and depression, which is rarely the case.

The cycles of bipolar disorder may be long or short, and the ups and downs may be of different magnitudes: for instance, a person suffering from bipolar disorder may suffer a protracted mild depression followed by a shorter and intense mania. The manic periods typically include euphoria, tirelessness, and impulsiveness; the depressed periods may seem much worse following a manic period.

Compliance with medications can be a major problem because people becoming manic lose insight, or an awareness of having an illness, and discontinue medications; then they often suffer a manic episode and may suddenly find themselves initiating multiple projects often being scattered and ineffective, or may go on a spending spree or take a poorly planned trip landing them in an unfamiliar location without cash. The manic periods, euphoric as they may be, are often disastrous because of the impulsiveness and irrationality that comes with them. Contrary to the patient's wishes, the depression does not respond instantaneously to resumed medication, typically taking 2-6 weeks to respond.

Bipolar disorder appears to run in families, that is, a vulnerablility for bipolar disorder may be genetically inherited. The rate of suicide is higher in people who have bipolar disorder than in the general population. The rate of prevalence of bipolar disorder is roughly equal (around 1%) in men and women.

Whilst bipolar disorder can be one of the most severe and devastating medical conditions, many individuals with bipolar disorder can also live full and mostly happy lives with correct management of their condition. Unlike patients with schizophrenia, persons with bipolar disorder have periods of normal
functioning between the extremes of mood.

Many famous people have been affected by bipolar disorder, including Spike Milligan, Lord Byron and Winston Churchill. There appears to be an association between bipolar disorder and talent in many cases - this is documented in Jamison's book "Touched with Fire".